Mask CD uniformity improvement by dry etching loading effect correction

Abstract

Proximity effect and foggy effect correction is performed to obtain an ideal CD distribution of resist patterns within a mask plate. However, gobal loading effect in dry etching causes an additional CD distribution of Cr patterns. In order to satisfy the CD distribution specification in 65nm node, CD distribution in global loading effect should be improved to be 2nm or less. To accomplish the goal, a correction system of dry etching loading effect has been developed. The correction is performed by sizing patterns in each writing field (1mm x 1mm). The sizing amount, minimum step of 1nm, is calculated according to the parameters, which are defined by measuring the test patterns. The loading effect is evaluated by measuring the CD difference of 1 micron lines and spaces in 80mm x 40mm clear area and that in completely dark area, which is an extremely severe case. The writer is JEOL/JBX-3030, and the dry etcher is Unaxia/VLR700GIII in the experiment. By applying this correction, CD uniformity caused by the global loading effect can be reduced to 2nm or less.